The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.
In some communication systems, one or more communication devices employ multiple antennas. When a transmitter with multiple antennas does not have information regarding a multiple-input, multiple-output (MIMO) or multiple-input, single-output (MISO) channel between the transmitter and a receiver, the transmitter may employ transmit diversity. For example, a transmitter utilizes delay diversity by transmitting a signal via a first transmitter and transmitting a time-delayed version of the signal via a second transmitter. As another example, a transmitter utilizes delay diversity by transmitting a signal via a first transmitter and a transmitting a frequency-offset version of the signal via a second transmitter. With antenna switching, a transmitter may choose a “best” antenna from a plurality of antennas, and then transmit using only the chosen antenna.
When a transmitter has MIMO or MISO channel information, the transmitter may develop a beamforming vector using the channel information to apply complex-valued weights at each antenna to steer a beam towards the receiver.